This invention relates to a method and an apparatus for detecting the motion (conveyance) of a sliver as it emerges, for example, from a carding machine.
In the manufacture of textile slivers such as carded slivers, the sliver has to be conveyed from one processing station to another, for example, to a storage arrangement such as a sliver coiler and can. Such a conveyance (sliver feed) has to proceed in a strictly prescribed, disturbance-free manner and must therefore be carefully monitored. In particular, breakage of the sliver may lead to problems and must therefore be recognized in a rapid and reliable manner. For this purpose optical systems, such as one-way optical gates or optical proximity switches are being used. These known arrangements have the disadvantage that they are unable to distinguish whether the sliver to be sensed is moved (which means that sliver production is in progress) or whether it is stationary (no production). These known systems can only determine whether a sliver is present in or absent from the detecting range. Due to this limitation, under certain conditions a breakage of sliver can only be unreliably detected, if at all. It is a particular disadvantage that a non-conveyance of the sliver can also not be detected when the sliver is present but is at a standstill. The optical barrier merely shows the presence of the sliver independently of whether the sliver moves or is stationary.